Catalysts and processes for the polymerization of olefins

ABSTRACT

Catalysts for the polymerization of olefins comprise the product of the reaction between: (A) a titanium, zirconium or hafnium product with substituted cyclopentadiene ligands, (B) a mixture of two organometallic aluminium compounds, with at least one of the groups bound to the aluminium being other than a linear alkyl, and (C) water. When used in the polymerization of olefins, these catalysts show higher activities, at short residence times, than corresponding catalysts obtained from the individual components of the above-mentioned mixtures of aluminium compounds.

This is a continuation of U.S. application Ser. No. 08/793,863, filed,May 7, 1997, now U.S. Pat No. 6,191,240, which is a 371 ofPCT/EP96/02615, filed Jun. 18, 1996.

The present invention relates to catalysts for the polymerization ofolefins, obtained from cyclopentadienyl compounds, organometallicaluminium compounds and water. Homogeneous catalyst systems for thepolymerization of olefins are known which comprise a metallocene and theproduct of the reaction between water and an aluminium alkyl, where thealkyl is other than methyl.

In European Patent Application EP 384 171, catalysts are described whichare suitable for the polymerization of olefins and comprise the productof the reaction between:

(A) a metallocene compound of the general formula:

(C₅R′_(n))_(m)R″_(p)(C₅R′_(n))MX_(3−m)

where (C₅R′_(n)) is a cyclopentadienyl group in which R′ is hydrogen, analkyl, alkenyl, aryl, alkylaryl or arylalkyl radicals having from 1 to20 C atoms or a group CR₂SiR₃ or a group SiR₃ with R being defined asfor R′, or two (or four) substituents R′ of one and the samecyclopentadienyl group form one (or two) rings having from 4 to 6 Catoms, R″ is a divalent radical selected from an optionally substitutedalkylene group having from 1 to 8 C atoms, an SiR₂, PR or NR group withR being defined as for R′, which forms a bridge link between twocyclopentadienyl groups, X is hydrogen, halogen, —OMX(C₅R′_(n))₂, —OH or—OR with R being defined as for R′, or a hydrocarbon radical having themeaning of R′, M is a transition metal of valency 3 or 4, selected fromTi, Zr or Hf, p is 0 or 1, m is 0, 1 or 2, and, if m=0, p=0 and, if p=0,at least one radical R′ is other than hydrogen, n=4, if p=1, and n=5, ifp=0; and

(B) an alumoxane of the formula:

in which R¹, R², R³ and R⁴ can generically be alkyl, alkenyl oralkylaryl radicals having 2-20 carbon atoms.

The alumoxanes (B) can be prepared by reacting the correspondingtrialkylaluminium with water in a 2:1 molar ratio. In the embodimentexamples, alumoxanes are used in which R¹, R² ₁ R³ and R⁴ are ethyl,isobutyl or 2-methylpentyl groups.

European Patent Application EP 575 875 describes homogeneous catalystsystems for the polymerization of olefins, obtained by contacting thefollowing components:

(A) a cyclopentadienyl compound of the general formula:

(C₅R¹ _(x−m)H_(5−x))R² _(m)(C₅R¹ _(y−m)H_(5−y))_(n)MQ_(3−n)

in which M is Ti, Zr or Hf, C₅R¹ _(x−m)H_(5−x) and C₅R¹ _(y−m)H_(5−y)are cyclopentadiene rings substituted in the same way or different ways,the substituents R¹ which can be identical or different are alkyl,alkenyl, aryl, alkylaryl or arylalkyl radicals which have from 1 to 20carbon atoms and can also contain Si or Ge atoms, or are Si(CH₃)₃groups, or also two or four substituents R¹ of one and the samecyclopentadienyl group can form one or two rings having from 4 to 6carbon atoms, R² is a group forming a bridge link between the twocyclopentadiene rings and is selected from CR³ ₂, C₂R³ ₄, SiR³ ₂, Si₂R³₄, GeR³ ₂, Ge₂R³ ₄, R³ ₂, SiCR³ ₂, NR¹ or PR¹, with the substituents R³which can be identical or different being R¹ or hydrogen, or also two orfour substituents R³ can form one or two rings having from 3 to 6 carbonatoms, the substituents Q which can be identical or different arehalogen, hydrogen, OH, SH, R¹, OR¹, SR¹, NR¹ ₂ or PR¹ ₂, m can be 0 or1, n can be 0 or 1, being 1 if m=1, x is an integer between (m+1) and 5,and y is an integer between m and 5;

(B) an organometallic aluminium compound of the general formula AlR³_(3−z)H_(z), in which the substituents R³ which can be identical ordifferent are alkyl, alkenyl or alkylaryl radicals which have from 1 to10 carbon atoms and can also contain Si or Ge atoms, with the provisothat at least one the substituents R³ is other than a linear alkylgroup, and z is 0 or 1; and

(C) water.

The molar ratio between the organometallic aluminium compound and thewater is between 1:1 and 100:1. In the embodiment examples, theorganometallic aluminium compounds used are only triisobutylaluminiumand triisohexylaluminium.

In Italian Patent Application No. MI/94A/1516, homogeneous catalystsystems for the polymerization of olefins are described which possess anactivity improved over those exemplified in the abovementioned patentapplication EP 575 875, which systems comprise the product obtained bycontacting the following components:

(A) a cyclopentadienyl compound of the formula:

(C₅R¹ _(x−m)H_(5−x))R² _(m)(C₅R¹ _(y−m)H_(5−y))_(n)MQ_(3−n)

in which M is Ti, Zr or Hf; C₅R¹ _(x−m)H_(5−x) and C₅R¹ _(y−m)H_(5−y)are cyclopentadiene rings substituted in the same way or different ways,the substituents R¹ which can be identical or different are alkyl,alkenyl, aryl, alkylaryl or arylalkyl radicals which have from 1 to 20carbon atoms and can also contain Si or Ge atoms, or are Si(CH₃)₃groups, or also two or four substituents R¹ of one and the samecyclopentadienyl group can form one or two rings having from 4 to 6carbon atoms, R² is a group forming a bridge link between the twocyclopentadiene rings and is selected from CR³ ₂, C₂R³ ₄, SiR³ ₂, Si₂R³₄, GeR³ ₂, Ge₂R³ ₄, R³ ₂SiCR³ ₂, NR¹ or PR¹, with the substituents R³which can be identical or different being R¹ or hydrogen, or also two orfour substituents R³ can form one or two rings having from 3 to 6 carbonatoms, the substituents Q which can be identical or different arehalogen, hydrogen, R¹, OR¹, SR¹, NR¹ ₂ or PR¹ ₂, m can be 0 or 1, n canbe 0 or 1, being 1, if m=1, x is an integer between (m+1) and 5 and y isan integer between m and 5;

(B) an organometallic aluminium compound of the formula:

Al—(CH₂—CR⁴R⁵R⁶)_(3−z)H_(z)

in which R⁴ is an alkyl, alkenyl or arylalkyl group having from 1 to 10carbon atoms, R⁵ is an alkyl, alkenyl or alkylaryl group with a branchedchain having from 3 to 10 carbon atoms, or R⁴ and R⁵ are fused togetherto form a ring having from 4 to 6 carbon atoms, R⁶ is hydrogen or analkyl, alkenyl or arylalkyl group having from 1 to 10 carbon atoms and zis 0 or 1; and

(C) water.

The molar ratio between the organometallic aluminium compound and thewater is between 1:1 and 100:1.

The polymerization yields of the catalysts described in theabovementioned patent applications are, albeit relatively high, notaltogether satisfactory if the residence times of the reaction mixturein the reactor are short. This is particularly important in industrialpolymerization processes, especially in those which operatecontinuously, where it is very advantageous to operate with shortresidence times.

It would therefore be desirable to improve the productivity of theabovementioned catalysts at short residence times.

BRIEF DESCRIPTION OF THE INVENTION

A It has now been found, unexpectedly, that catalysts for thepolymerization of olefins, of the type of those described in theabovementioned patent applications, obtained from particular mixtures oforganometallic aluminium compounds, show superior activities at shortresidence times than the corresponding catalysts obtained from theindividual components of the abovementioned mixtures of aluminiumcompounds.

BRIEF DESCRIPTION OF THE DRAWING

The drawing shows, for examples 1-5, the relationship of the total gramsof feed monomers per gram Zr to the polymerization time in minutes.

DETAILED DESCRIPTION OF THE INVENTION

The catalysts which are the subject of the present invention comprisethe product obtained by contacting the following components:

(A) a cyclopentadienyl compound of the formula (I):

(C₅R¹ _(x−m)H_(5−x))R² _(m)(C₅R¹ _(y−m)H_(5−y))_(n)MQ_(3−n)  (I)

in which M is Ti, Zr or Hf, C₅R¹ _(x−m)H_(5−x) and C₅R¹ _(y−m)H_(5−y)are cyclopentadiene rings substituted in the same way or different ways,the substituents R¹ which can be identical or different are alkyl,alkenyl, aryl, alkylaryl or arylalkyl radicals which have from 1 to 20carbon atoms and can also contain Si or Ge atoms, or Si(CH₃)₃ groups, oralso two or four substituents R¹ of one and the same cyclopentadienylgroup can form one or two rings having from 4 to 6 carbon atoms, R² is agroup forming a bridge link between the two cyclopentadiene rings and isselected from CR³ ₂, C₂R³ ₄, SiR³ ₂, Si₂R³ ₄, GeR³ ₂, Ge₂R³ ₄, R³ ₂SiCR³₂, NR¹ or PR¹ with the substituents R³ which can be identical ordifferent being R¹ or hydrogen, or also two or four substituents R³ canform one or two rings having from 3 to 6 carbon atoms, the substituentsQ which can be identical or different are halogen, hydrogen, R¹, OR¹,SR¹, NR¹ ₂ or PR¹ ₂ m can be 0 or 1, n can be 0 or 1, being 1, if m=1, xis an integer between (m+1) and 5, and y is an integer between m and 5;

(B) a mixture composed of:

(B1) 1-99 mol-% of an organometallic aluminium compound of the formula(II):

Al—(CH₂—CR⁴R⁵R⁶)_(3−z)H_(z)  (II)

in which R⁴ is an alkyl, alkenyl or arylalkyl group having from 1 to 10carbon atoms, R⁵ is an alkyl, alkenyl or alkylaryl group with a branchedchain having from 3 to 10 carbon atoms, or R⁴ and R⁵ are fused togetherto form a ring having from 4 to 6 carbon atoms, R⁶ is hydrogen or analkyl, alkenyl or arylalkyl group having from 1 to 10 carbon atoms, andz is 0 or 1;

(B2) 1-99 mol-% of an organometallic aluminium compound of the formula(III):

AlR³ _(3−w)H_(w)  (III)

in which the substituents R³ which can be identical or different arealkyl, alkenyl or alkylaryl radicals which have from 1 to 10 carbonatoms and can also contain Si or Ge atoms, with the proviso that atleast one of the substituents R³ is other than a linear alkyl group, andw is 0 or 1, the compounds of the formula (II) defined above beingexcluded; and

(C) water.

The molar ratio between the total of the organometallic aluminiumcompounds and the water is between 1:1 and 100:1, preferably between 1:1and 50:1 and more preferably between 1:1 and 10:1.

The molar ratio between the aluminium and the metal of thecyclopentadienyl compound is between about 50 and 10,000, preferablybetween about 500 and 5000 and more preferably between 1000 and 2000.

The molar ratio (B1)/(B2) between the two components of the mixture (B)of organometallic aluminium compounds is preferably between about 10:90and about 90:10, and more preferably is between about 25:75 and about75:25. Those mixtures (B) are particularly preferred in which thecomponents (B1) and (B2) are present in approximately equimolarquantities.

In the case of m=0, particularly suitable cyclopentadienyl compounds arethose in which M is Zr and the groups C₅R¹ _(x−m)H_(5−x) and C₅R¹_(y−m)H_(5−y) are pentamethyl-cyclopentadienyl, indenyl or4,5,6,7-tetrahydroindenyl, while the substituents Q are chlorine atomsor hydrocarbon groups containing from 1 to 7 carbon atoms.

Non-limiting examples of cyclopentadienyl compounds (A) with m=0 are:

(Me₃Cp)₂MCl₂ (Me₄Cp)₂MCl₂ (Me₅Cp)₂MCl₂ (Me₅Cp)₂MMe₂ (Me₅Cp)₂M(OMe)₂(Me₅Cp)₂M(C₆H₅)₂ (Me₅CP)₂M(CH₃)Cl (EtMe₄Cp)₂MCl₂ [(C₆H₅)Me₄Cp]₂MCl₂(Et₅Cp)₂MCl₂ (Me₅Cp)₂M(C₆H₅)Cl (Ind)₂MCl₂ (Ind)₂MMe₂ (H₄Ind)₂MCl₂(H₄Ind)₂MMe₂ [Si(CH₃)₃Cp]₂MCl₂ {[Si(CH₃)₃]₂Cp}₂MCl₂ (Me₄Cp)(Me₅Cp)MCl₂(Me₅Cp)MCl₃ (Me₅Cp)MBenz₃ (Ind)MBenz₃ (H₄Ind)MBenz₃

where Me=methyl, Et=ethyl, Cp=cyclopentadienyl, Ind=indenyl,H₄Ind=4,5,6,7-tetrahydroindenyl, Benz=benzyl, M is Ti, Zr or Hf andpreferably is Zr.

In the case of m=1, particularly suitable cyclopentadienyl compounds arethose in which M is Zr and the groups C₅R¹ _(x−m)H_(5−x) and C₅R¹_(y−m)H_(5−y) are tetramethyl-cyclopentadienyl, indenyl ortetrahydroindenyl and R² is a group (CH₃)₂Si or C₂H₄, while thesubstituents Q are chlorine atoms or hydrocarbon groups having from 1 to7 carbon atoms.

Non-limiting examples of cyclopentadienyl compounds (A) with M=1 are:

Me₂Si(Me₄Cp)₂MCl₂ Me₂Si(Me₄Cp)₂MMe₂ Me₂C(Me₄Cp)(MeCp)MCl₂Me₂Si(Ind)₂MCl₂ Me₂CSi(Ind)₂MMe₂ Me₂Si(Me₄Cp)₂MCl(OEt) C₂H₄(Ind)₂MCl₂C₂H₄(Ind)₂MMe₂ C₂H₄(Ind)₂M(NMe₂)₂ C₂H₄(H₄Ind)₂MCl₂ C₂H₄(H₄Ind)₂MMe₂C₂H₄(H₄Ind)₂M(NMe₂)OMe Ph(Me)Si(Ind)₂MCl₂ Ph₂Si(Ind)₂MCl₂Me₂C(Flu)(Cp)MCl₂ C₂H₄(Me₄Cp)₂MCl₂ C₂Me₄(Ind)₂MCl₂ Me₂SiCH₂(Ind)₂MCl₂C₂H₄(2-MeInd)₂MCl₂ C₂H₄(3-MeInd)₂MCl₂ C₂H₄(4,7-Me₂Ind)₂MCl₂C₂H₄(5,6-Me₂Ind)₂MCl₂

where Me=methyl, Cp=cyclopentadienyl, Ind=indenyl, Flu=fluorenyl,Ph=phenyl, H₄Ind=4,5,6,7-tetrahydroindenyl, M is Ti, Zr or Hf andpreferably is Zr.

In the organometallic aluminium compound of the formula (II) which canbe used as component (B1), R⁴ is preferably a methyl or ethyl group,while R⁶ is preferably a hydrogen atom.

Particularly preferred as components (B1) are the organometallicaluminium compounds in which R⁴ is a methyl group, R⁵ is an alkyl groupwith a branched chain having a number of carbon atoms greater than 4 andR⁶ is a hydrogen atom.

Non-limiting examples of organometallic aluminium compounds which can beused as components (B1) are: tris-(2,4,4-trimethyl-pentyl)-aluminium anddi-(2,4,4-trimethyl-pentyl)-aluminium hydride. The particularlypreferred compound is tris-(2,4,4-trimethyl-pentyl)-aluminium (TIOA).

In the organometallic aluminium compound of the formula (II) which canbe used as component (B1), preferably all the substituents R⁷ arenon-linear alkyl, alkenyl or alkylaryl radicals. More preferably, allthe substituents R⁷ of the organometallic aluminium compound areisoalkyl radicals.

Non-limiting examples of organometallic aluminium compounds which can beused as components (B2) are:

triethylaluminium,

di-methylisobutylaluminium,

methyl-di-isobutylaluminium,

tri-isobutylaluminium,

di-isobutylaluminium monohydride and

tris-(2,2-dimethylpropyl)aluminium.

The particularly preferred compound is triisobutylaluminium (TIBA).

The components constituting the catalysts of the present invention canbe brought into contact in various ways.

In an embodiment example, the mixture of aluminium compounds iscontacted with water, and then the reaction product thus obtained isbrought into contact with the cyclopentadienyl compound.

A further subject of the present invention is therefore a catalyst forthe polymerization of olefins, comprising the product obtained bycontacting the following components:

(A) a cyclopentadienyl compound of the formula (I):

(C₅R¹ _(x−m)H_(5−x))R² _(m)(C₅R¹ _(y−m)H_(5−y))_(n)MQ_(3−n)  (I)

in which M is Ti, Zr or Hf, C₅R¹ _(x−m)H_(5−x)and C₅R¹ _(y−m)H_(5−y) arecyclopentadiene rings substituted in the same way or different ways, thesubstituents R¹ which can be identical or different are alkyl, alkenyl,aryl, alkylaryl or arylalkyl radicals which have from 1 to 20 carbonatoms and can also contain Si or Ge atoms, or Si(CH₃)₃ groups, or alsotwo or four substituents R¹ of one and the same cyclopentadienyl groupcan form one or two rings having from 4 to 6 carbon atoms, R² is a groupforming a bridge link between the two cyclopentadiene rings and isselected from CR³ ₂, C₂R³ ₄, SiR³ ₂, Si₂R³ ₄, GeR³ ₂, Ge₂R³ ₄, R³ ₂SiCR³₂, NR¹ or PR¹, with the substituents R³ which can be identical ordifferent being R¹ or hydrogen, or also two or four substituents R³ canform one or two rings having from 3 to 6 carbon atoms, the substituentsQ which can be identical or different are halogen, hydrogen, R¹, OR¹,SR¹, NR¹ ₂ or PR¹ ₂, m can be 0 or 1, n can be 0 or 1, being 1, if m=1,x is an integer between (m+1) and 5, and y is an integer between m and5; and

(B) the product of the reaction between water and a mixture consistingof:

(B1) 10-90 mol-% of an organometallic aluminium compound of the formula(II):

Al—(CH₂—CR⁴R⁵R⁶)_(3−z)H_(z)  (II)

in which R⁴ is an alkyl, alkenyl or arylalkyl group having from 1 to 10carbon atoms, R⁵ is an alkyl, alkenyl or alkylaryl group with a branchedchain having from 3 to 10 carbon atoms, or R⁴ and R⁵ are fused togetherto form a ring having from 4 to 6 carbon atoms, R⁶ is hydrogen or analkyl, alkenyl or arylalkyl group having from 1 to 10 carbon atoms, andz is 0 or 1; and

(B2) 10-90 mol-% of an organometallic aluminium compound of the formula(III):

AlR³ _(3−w)H_(w)  (III)

in which the substituents R³ which can be identical or different arealkyl, alkenyl or alkylaryl radicals which have from 1 to 10 carbonatoms and can also contain Si or Ge atoms, with the proviso that atleast one of the substituents R³ is other than a linear alkyl group, andw is 0 or 1, the compounds of the formula (II) defined above beingexcluded.

The molar ratio between the organometallic aluminium compounds and thewater is between 1:1 and 100:1, preferably between 1:1 and 50:1, morepreferably between 1:1 and 10:1.

The components of the catalysts of the present invention can be broughtinto contact by various methods.

For example, it is possible gradually to add water to the mixture ofaluminium compounds in solution in an inert aliphatic or aromatichydrocarbon solvent such as, for example, heptane or toluene. Thesolution thus obtained is contacted with a solution of acyclopentadienyl compound in a suitable solvent as, for example,toluene.

According to another way of proceeding, the water can be introduced inthe monomer, or in one of the monomers, to be polymerized; in this case,the mixture of aluminium compounds and the cyclopentadienyl compound arefirst brought into contact before they are used in the polymerization.Moreover, the water can be made to react in a combined form as ahydrated salt, or it can be adsorbed or absorbed on an inert supportsuch as silica. Another preparation method is the reaction of thealuminium compounds with boric anhydride or boric acid.

The catalysts of the present invention can also be used on inertsupports. This is effected by depositing the cyclopentadienyl compound,or the product of the reaction thereof with the aluminium compoundspre-reacted with water, or the aluminium compounds pre-reacted withwater and then the cyclopentadienyl compound, on inert supports such as,for example, silica, alumina, styrene/ divinylbenzene copolymers,polyethylene or polypropylene.

A particularly suitable class of inert supports which can be used isthat constituted by porous organic supports functionalized with groupshaving active hydrogen atoms. Those are particularly preferred in whichthe organic support is a partially crosslinked styrene polymer. Supportsof this type are described in European Application EP-633 272, thecontent of which is understood to be incorporated in the presentdescription.

The solid compound thus obtained, in combination with the furtheraddition of aluminium alkyl compounds, whether pre-reacted with water ornot, can be used in the gas-phase polymerization.

The catalysts of the present invention can be used in the polymerizationreactions of olefins.

A further subject of the present invention is therefore a process forthe polymerization of at least one olefin of the formula CH₂═CHR, inwhich R is hydrogen or an alkyl radical having from 1 to 20 carbonatoms, comprising the polymerization reaction of the said olefins in thepresence of a catalyst as described above.

The catalysts according to the present invention can advantageously beused in the homopolymerization of ethylene and, in particular, for thepreparation of HDPE, and for the copolymerization of ethylene and, inparticular, for the preparation of LLDPE.

The LLDPE copolymers which are obtained have a content of it ethyleneunits of between 80 and 99 mol-%. Their density is between 0.87 and 0.95g/cm³ and they are characterized by a uniform distribution of thecomonomer units within the polymer chain.

The olefins which can be used as comonomers comprise α-olefins of theformula CH₂═CHR, where R is a linear or branched or cyclic alkyl radicalhaving from 1 to 20 carbon atoms, or cycloolefins. Examples of sucholefins are propylene, 1-butene, 1-pentene, 4-methyl-1-pentene,1-hexene, 1-octene, allylcyclohexane, cyclopentene, cyclohexene,norbornene and 4,6-dimethyl-1-heptene. The units derived from theolefins of the formula CH₂═CHR or from the cycloolefins are present inthe copolymers in quantities from 1 to 20 mol-%.

The copolymers can also contain units derived from polyenes, inparticular conjugated or non-conjugated, linear or cyclic dienes suchas, for example, 1,4-hexadiene, isoprene, 1,3-butadiene, 1,5-hexadieneand 1,6-heptadiene.

A further use of interest is the preparation of elastomeric copolymersof ethylene with α-olefins of the formula CH₂═CHR, where R is an alkylradical having from 1 to 10 carbon atoms, the said copolymers optimallycontaining minor proportions of units derived from a polyene.

The saturated elastomeric polymers obtainable by means of the catalystsof the present invention contain from 15 to 85 mol-% of ethylene units,the complement up to 100 consisting of units of one or more α-olefinsand/or of one non-conjugated diolefin capable of cyclopolymerizing. Theunsaturated elastomeric copolymers contain, besides the units derivedfrom the polymerization of ethylene and α-olefins, also minorproportions of unsaturated units derived from the copolymerization ofone or more polyenes. The content of unsaturated units can vary from 0.1to 5% by weight and is preferably between 0.2 and 2% by weight.

The copolymers obtainable are characterized by valuable properties, suchas a low ash content and a uniform distribution of the comonomers in thecopolymer chain.

The α-olefins which can be used comprise, for example, propylene,1-butene and 4-methyl-1-pentene. The preferred α-olefin is propylene.

The non-conjugated diolefins capable of cyclopolymerizing, which can beused, are 1,5-hexadiene, 1,6-heptadiene and 2-methyl-1,5-hexadiene.

The polyenes capable of giving unsaturated units, which can be used,are:

conjugated dienes such as, for example, butadiene and isoprene;

non-conjugated linear dienes such as, for example, trans-1,4-hexadiene,cis-1,4-hexadiene, 6-methyl-1,5-heptadiene, 3,7-dimethyl-1,6-octadieneand 11-methyl-1,10-dodecadiene;

monocyclic diolefins such as, for example, cis-1,5-cyclooctadiene and5-methyl-1,5-cyclooctadiene;

bicyclic diolefins such as, for example, 4,5,8,9-tetrahydroindene and 6-and/or 7-methyl-4,5,8,9-tetrahydroindene;

alkenyl- or alkylidene-norbornenes such as, for example,5-ethylidene-2-norbornene, 5-isopropylidene-2-norbornene,exo-5-isopropenyl-2-norbornene and 5-vinyl-2-norbornene;

polycyclic diolefins such as, for example, dicyclopentadiene,tricyclo[6.2.1.0^(2,7)]4,9-undecadiene and its 4-methyl derivative.

Preferred polyenes are 5-ethylidene-2-norbornene, trans-1,4-hexadieneand cis-1,4-hexadiene. 5-Ethylidene-2-norbornene (ENB) is particularlypreferred.

The polymerization processes, which use the catalysts of the invention,can be carried out in the liquid phase, in the presence or absence of aninert hydrocarbon solvent, or in the gas phase. The hydrocarbon solventcan be aromatic such as toluene, or aliphatic such as propane, hexane,heptane, isobutane and cyclohexane.

The polymerization temperature is generally between −100° C. and 250° C.In particular, in the processes for the preparation of HDPE or LLDPE, itis generally between 20° C. and 150° C. and especially between 40° C.and 90° C. In the processes for the preperation of elastomericcopolymers, it is generally between 20° C. and 100° C. and especiallybetween 30° C. and 80° C.

The molecular weight of the polymers can be varied simply by alteringthe polymerization temperature, the type or the concentration of thecatalyst components or using molecular weight regulators such as, forexample, hydrogen.

The molecular weight distribution can be varied by using mixtures ofdifferent cyclopentadienyl compounds or by carrying out thepolymerization in several stages which differ in the polymerizationtemperatures and/or in the concentrations of the molecular weightregulator.

The catalyst components can be brought into mutual contact before thepolymerization. The contact time is generally between 1 and 60 minutes,preferably between 5 and 20 minutes. The pre-contact concentrations forthe cyclopentadienyl compound are between 10⁻² and 10⁻⁸ mol/l, while,for the product of the reaction between aluminium alkyl and water, theyare between 10 and 10⁻³ mol/l. The precontact is in general effected inthe presence of a hydrocarbon solvent and, if appropriate, smallquantities of monomer.

FIG. 1 shows a graph of the productivity, to give ethylene/propylenecopolymers, of catalysts according to the invention and according to theknown technology as a function of the polymerization time. This graphclearly shows the higher productivity of the catalysts according to theinvention as compared with known catalysts at short polymerizationtimes.

The following examples are given for illustrative purposes and do notlimit the invention.

Characterizations

The intrinsic viscosity [η] was measured in tetralin at 135° C.

The comonomer content in the elastomeric ethylene/propylene copolymerswas determined by IR.

The catalyst components were prepared as follows:

Cyclopentadienyl Compoundsrac-Ethylene-Bis(4,5,6,7-Tetrahydroindenyl)Zirconium Dichloride(r-EBTHIZrCl₂)

This was prepared according to the procedure described in EP 575,875.

Organometallic Aluminium Compounds Tri-Isobutylaluminium [TIBA]

The commercial product from WITCO was used.

Tris-(2,4,4-Trimethyl-Pentyl)-Aluminium [TIOA]

This was prepared according to the method described in Liebigs Ann.Chem. vol. 629, Ziegler et al. “Aluminumtrialkyle undDialkyl-aluminumhydride aus Aluminumisobutyl-Verbindungen [Aluminiumtrialkyls and dialkyl-aluminium hydrides from aluminium isobutylcompounds]”, pages 14-19.0.

EXAMPLES 1-3

Preparation of Elastomeric C₂/C₃-copolymers

1324 g (2 liters) of n-hexane, 44.7 g of ethylene, 388 g of propyleneand 0.94 mmol of water were introduced at ambient temperature into a4.25 liter autoclave fitted with stirrer, mano-meter, temperatureindicator, catalyst-charging system, monomer feed lines and thermostatjacket, and purified by purging with ethylene at 80° C.

The catalyst solution was prepared by adding the quantities of aluminiumalkyls given in Table 1 to a suspension of 0.8 mg of r-EBTHI₂ZrCl₂ in ahydrocarbon solvent consisting of about 2 ml of solvent per mg ofmetallocene. Stirring of the mixture was continued for 5 minutes at atemperature of 20° C., and the solution was then injected into theautoclave under ethylene pressure at a temperature about 2° C. lowerthan the polymerization temperature. The temperature was then raisedwithin about 2 minutes to 50° C. and kept constant for the wholeduration of the polymerization.

The pressure was kept constant at a value of 9.6 bar by feeding anethylene/propylene mixture in a 60:40 ratio. The consumption of monomersfed was monitored at regular time intervals (2 minutes) throughout thewhole duration of the polymerization. When the total quantity ofmonomers fed reached a value of 60 g, the reaction was stopped bydegassing the monomers. The polymer obtained was dried in an oven at 60°C. in vacuo.

The data relating to the polymerization and to the characterization ofthe copolymer obtained are given in Table 1.

The data relating to the consumption of monomers as a function of thepolymerization time are given in Table 2.

EXAMPLES 4-5

(Comparison)

Preparation of Elastomeric C₂/C₃-copolymers

The procedure described in Examples 1-3 was followed, but with thedifference that only one of the components of the mixture (B) ofaluminium compounds was used.

The data relating to the polymerization and to the characterization ofthe polymer obtained are given in Table 1. The data relating to themonomer consumption as a function of the polymerization time are givenin Table 2.

TABLE 1 C₂ units [η] TIBA TIOA Al/H₂O time (% by (dl/ EXAMPLE (mmol)(mmol) (mol) (min) weight) g) 1 0.94 0.94 2 31 57.3 3.75 2 0.47 1.41 233 55.6 3.70 3 1.41 0.47 2 39 62.3 4.20 4 1.88 0 2 59 63.1 4.56 (comp.)5 0 1.88 2 42 56.9 3.93 (comp.)

TABLE 2 polymerization total monomers fed (g) time EX. 4 EX. 5 (min) EX.1 EX. 2 Ex. 3 (comp) (comp)  2 0 0.2 1.3 3.9 0.1  4 5.8 5 12.1 6.8 4.1 6 13.9 12.4 17 8.3 8.2  8 20.8 19.4 20 10.5 11.6 10 26.2 24.6 23.6 12.314.8 12 30.7 29.1 27.5 14.1 17.9 14 34.5 33.1 31 16 20.9 16 38 36.7 3418 24.8 18 41.2 39.9 36.8 19.9 28.4 20 44.2 43.1 39.3 21.8 31.9 22 47.546.5 41.8 23.6 35.4 24 50.7 49.7 44.3 25.6 38.6 26 53.7 52.3 47 27.842.1 28 56.3 54.9 49.4 30 45.5 30 58.7 56.9 51.7 32.1 48.4 32 60* 58.953.8 34.3 51.1 34 60• 55.7 36.3 53.3 36 57.4 38.3 55.2 38 58.9 40.1 56.940 60 42 58.3 42 43.8 60 44 45.7 46 47.5 48 49.3 50 51.3 52 53.2 54 55.256 57 58 58.6 59 60 *31 minutes •33 minutes

What is claimed is:
 1. Catalyst for the polymerization of olefins,comprising the product of the reaction between the following components:(A) a cyclopentadienyl compound of the formula (I): (C₅R¹_(x−m)H_(5−x))R² _(m)(C₅R¹ _(y−m)H_(5−y))_(n)MQ_(3−n)  (I)  in which Mis Ti, Zr or Hf, C₅R¹ _(x−m)H_(5−x) and C₅R¹ _(y−m)H_(5−y) arecyclopentadiene rings substituted in the same way or different ways, thesubstituents R¹, which are identical or different, are alkyl, alkenyl,aryl, alkylaryl or arylalkyl radicals which have from 1 to 20 carbonatoms and can also contain one or more Si atoms, or Si(CH₃)₃ groups, oralso two or four substituents R¹ of the same cyclopentadienyl group canform one or two rings having from 4 to 6 carbon atoms, R² is a groupforming a bridge link between the two cyclopentadiene rings and isselected from the group consisting of CR³ ₂, C₂R³ ₄, SiR³ ₂, Si₂R³ ₄,GeR³ ₂, Ge₂R³ ₄, R³ ₂SiCR³ ₂, NR¹, and PR¹; substituents R³, which areidentical or different, being Ror hydrogen, and two or four substituentsR³ can form one or two rings having from 3 to 6 carbon atoms, theradicals Q, which are identical or different, are halogen, hydrogen, R¹or OR¹, SR¹, NR¹ ₂ or PR¹ ₂, m is 0 or 1, n is 0 or 1, being 1, if m=1,x is an integer between (m+1) and 5, and y is an integer between m and5; (B) a mixture composed of: (B1) 1-99 mol-% of an organoaluminiumcompound of the formula (II): Al—(CH₂—CR⁴R⁵R⁶)_(3−z)H_(z)  (II)  inwhich R⁴ is an alkyl, alkenyl or arylalkyl group having from 1 to 10carbon atoms, R⁵ is an alkyl, alkenyl or alkylaryl group with a branchedchain having from 3 to 10 carbon atoms, or R⁴ and R⁵ are fused togetherto form a ring having from 4 to 6 carbon atoms, R⁶ is hydrogen or analkyl, alkenyl or arylalkyl group having from 1 to 10 carbon atoms, andz is 0 or 1; (B2) 1-99 mol-% of an organoaluminium compound of theformula (III): AlR³ _(3−w)H_(w)  (III) in which the radicals R³, whichare identical or different, are alkyl, alkenyl or alkylaryl radicalswhich have from 1 to 10 carbon atoms and can also contain Si or Geatoms, with the proviso that at least one of the substituents R³ isother than a linear alkyl group, and w is 0 or 1, the compounds of theformula (II) defined above being excluded; and (C) water, the molarratio between the organometallic aluminium compounds and the water beingbetween 1:1 and 100:1.
 2. Catalyst according to claim 1, wherein themolar ratio between the organoaluminium compound and the water isbetween 1:1 and 10:1.
 3. Catalyst according to claim 1, wherein themolar ratio between the aluminium of the organoaluminium compounds andthe metal M of the cyclopentadienyl compound is between 50 and 10,000.4. Catalyst according to claim 1, wherein in the cyclopentadienylcompound (A), m=0. the groups C₅R¹ _(x−m)H_(5−x) and C₅R¹ _(y−m)H_(5−y)are pentamethylcyclopentadienyl, indenyl or 4,5,6,7-tetrahydroindenyl, Mis Zr and the radicals Q are chlorine atoms or hydrocarbon groupscontaining from 1 to 7 carbon atoms.
 5. Catalyst according to claim 1,wherein in the cyclopentadienyl compound (A), m=1, n=1, R² is a divalentgroup (CH₃)₂Si or C₂H₄ and the groups C₅R¹ _(x−m)H_(5−x) and C₅R¹_(y−m)H_(5−y) are selected from the group consisting oftetramethyl-cyclopentadienyl, indenyl 4,5,6,7-tetrahydroindenyl,2-methyl-4,5,6,7-tetrahydroindenyl,4,7-dimethyl-4,5,6,7-tetrahydroindenyl,2,4,7-trimethyl-4,5,6,7-tetrahydroindenyl and fluorenyl.
 6. Catalystaccording to claim 1, wherein in the cyclopentadienyl compound of theformula (I) the radicals Q are chlorine atoms or methyl groups. 7.Catalyst according to claim 1, wherein in the organoaluminium compoundsof the formula (II) R⁴ is a methyl or ethyl group.
 8. Catalyst accordingto claim 1 wherein in the organoaluminium compounds of the formula (II)R⁶ is hydrogen.
 9. Catalyst according to claim 8, wherein in theorganoaluminium compounds of the formula (II) R⁴ is a methyl group andR⁵ is an alkyl group with a branched chain having a number of carbonatoms greater than
 4. 10. Catalyst according to claim 1, wherein theorganoaluminium compounds of the formula (II) istri-(2,4,4-trimethyl-pentyl)-aluminium.
 11. Catalyst for thepolymerization of olefins, comprising the product of the reactionbetween the following components: (A) a cyclopentadienyl compound of theformula (I) (C₅R¹ _(x−m)H_(5−x))R² _(m)(C₅R¹_(y−m)H_(5−y))_(n)MQ_(3−n)  (I)  in which M is Ti, Zr or Hf, C₅R¹_(x−m)H_(5−x) and C₅R¹ _(y−m)H_(5−y) are cyclopentadiene ringssubstituted in the same way or different ways, the substituents R¹,which are identical or different are alkyl, alkenyl, aryl, alkylaryl orarylalkyl radicals which have from 1 to 20 carbon atoms and also containone or more Si atoms, or Si(CH₃)₃ groups, or also two or foursubstituents R¹ of the same cyclopentadienyl group can form one or tworings having from 4 to 6 carbon atoms. R² is a group forming a bridgelink between the two cyclopentadiene rings and is selected from thegroup consisting of CR³ ₂, C₂R³ ₄, SiR³ ₂, Si₂R³ ₄, GeR³ ₂, Ge₂R³ ₄, R³₂SiCR³ ₂, NR¹, and PR¹, substituents R³, which are identical ordifferent, being R¹ or hydrogen, or also two or four substituents R³ canform one or two rings having from 3 to 6 carbon atoms, the radicals Q,which are identical or different, are halogen, hydrogen, R¹ or OR¹, SR¹,NR¹ ₂ or PR¹ ₂, m is 0 or 1, n is 0 or 1, being 1, if m=1, x is aninteger between (m+1) and 5, and y is an integer between m and 5; and(B) the product of the reaction between water and a mixture composed of:(B1) 10-90 mol-% of an organoaluminium compound of the formula (II):Al—(CH₂—CR⁴R⁵R⁶)_(3−z)H_(z)  (II)  in which R⁴ is an alkyl, alkenyl orarylalkyl group having from 1 to 10 carbon atoms, R⁵ is an alkyl,alkenyl or alkylaryl group with a branched chain having from 3 to 10carbon atoms, or R⁴ and R⁵ are fused together to form a cycle havingfrom 4 to 6 carbon atoms, R⁶ is hydrogen or an alkyl, alkenyl orarylalkyl group having from 1 to 10 carbon atoms, and z is 0 or 1; and(B2) 10-90 mol-% of an organoaluminium compound of the formula (III):AlR³ _(3−w)H_(w)  (III) in which the radicals R³, which are identical ordifferent, are alkyl, alkenyl or alkylaryl radicals which have from 1 to10 carbon atoms and can also contain Si or Ge atoms, with the provisothat at least one of the substituents R³ is other than a linear alkylgroup, and w is 0 or 1, the compounds of the formula (II) defined abovebeing excluded; the molar ratio between the organometallic aluminiumcompounds and the water being between 1:1 and 100:1.
 12. Process for thepolymerization of at least one olefin of the formula CH₂═CHR, in which Ris hydrogen or an alkyl, cycloalkyl or aryl radical having from 1 to 20carbon atoms, comprising the polymerization reaction of said olefins inthe presence of a catalyst according to claim
 1. 13. Process for thepreparation of ethylene homopolymers, comprising the polymerizationreaction of ethylene in the presence of a catalyst according to claim11.
 14. Process for the preparation of ethylene copolymers with one ormore α-olefins of the formula CH₂═CHR, where R is a linear, branched orcyclic alkyl radical having from 1 to 20 carbon atoms or a cycloolefin,the said copolymers containing from 80 to 99 mol-% of ethylene units andfrom 1 to 20 mol-% of alpha-olefin or cycloolefin units and optionallyminor proportions of polyene units, comprising the polymerizationreaction of the ethylene as a mixture with the α-olefin(s) orcycloolefin(s) and optionally with the polyene in the presence of acatalyst according to claim
 1. 15. Process for the preparation ofelastomeric ethylene copolymers with one or more alpha-olefins of theformula CH₂═CHR, where R is an alkyl radical having from 1 to 10 carbonatoms, the said copolymers optionally containing minor proportions ofpolyene units, comprising the polymerization reaction of the ethylene asa mixture with one or more alpha-olefins and optionally with minorproportions of a polyene in the presence of a catalyst according toclaim
 1. 16. Process according to claim 15, wherein the copolymerscontain from 15 to 85 mol-% of ethylene and from 85 to 15 mol-% of analpha-olefin selected from the group from propylene, 1-butene and4-methyl-1-pentene.
 17. Process according to claim 15, wherein thecopolymers contain from 15 to 85 mol-% of ethylene and from 85 to 15mol-% of an alpha-olefin selected from the group consisting ofpropylene, 1-butane and 4-1-pentene.
 18. The catalyst for thepolymerization of olefins according to claim 11 in which saidcyclopentadienyl compound of said formula (I) israc-ethylene-bis(4,5,6,7-tetrahydroindenyl) Zirconium dichloride, saidorganoaluminium compound of formula (II) is tri-isobutylaluminium andsaid organoaluminium compound of formula (III) istris-(2,4,4-trimethyl-pentyl)-aluminium.
 19. The process according toclaim 18, wherein the copolymers contain from 15 to 85 mol-% of ethyleneand form 85 to 15 mol-% of an alpha-olefin selected from the groupconsisting of propylene, 1-butene and 4-methyl-1-pentene.
 20. Thecatalyst for the polymerization of olefins according to claim 1 in whichthe combination of said organoaluminium compound of formula (II) andsaid organoaluminium compound of formula (III) produces superioractivity at shorter residence times than a catalyst using only one ofsaid organoaluminium compound of formula (II) and said organoaluminiumcompound of formula (III).
 21. The catalyst for the polymerization ofolefins according to claim 11 in which the combination of saidorganoaluminium compound of formula (II) and said organoaluminiumcompound of formula (III) produces superior activity at shorterresidence times than a catalyst using only one of said organoaluminiumcompound of formula (II) and said organoaluminium compound of formula(III).